[img]/forums/images/icons/smile.gif[/img] Pat, the Hydramatics were probably the longest-lived in terms of actual production and use in many, many different GM products. The Hydramatics were used in quite a few other makes of vehicles, including army tanks in WWII. The M-3 Stuart had twin flathead Caddies with Hydros behind them. 1957 was the last year for Oldsmobile and Pontiac Hydramatics and alas, they came out in '58 with a box known as a Jet-a-way. It was their first whack at an aluminum case transmission and the first try at several other things as well. The Jet-a-ways were absolutly no good, gave lots of trouble and defied solutions. The only good part was that it finally led GM to the Turbo-Hydramatic, which, after a few years and a few changes was an OK box. BY FAR the Chrysler stuff was the best, most trouble-free of all. The two-sp Power-Flite and the 3-sp Torque-Flite were unstoppable. [img]/forums/images/icons/cool.gif[/img] More than any other mfg., GM kept the automatic transmission shops in business. [img]/forums/images/icons/crazy.gif[/img] The Turbo 400 as used in the Caddy, the Olds, the Shiv-Lay, and the Ponchos was their best effort of all. It was as good as the Hydramatic and a lot less weight. Also, when you pulled one, you didn't have THIRTY-TWO bolts to take out of the torque converter with fluid running down your sleeves [img]/forums/images/icons/crazy.gif[/img] like you did when you jerked a Hydramatic out. [img]/forums/images/icons/tongue.gif[/img] GM quit putting the TH400 in the Caddy ONLY because there was no way to keep it from jerking Mrs. Van Snoot when she put the car in gear. A Jeep buddy has long since figured out how to keep them from doing that, but for some reason GM never did. [img]/forums/images/icons/smile.gif[/img]